here are two links where you can cancel the membership:
If necessary and for further questions click through http://helpx.adobe.com/contact.html and if "open" please use chat, I had the best experiences. I quote from Adobe's employee Preran: The chat button is activated as soon as there is an agent available to help.
On the other hand you have to look at Subscription Terms >>> http://www.adobe.com/misc/subscription_terms.html to see the conditions for a (early) cancellation.
After that procedure you can conduct your other membership.